Device for depositing a light-diffusing coating on surfaces



1954 G. G. J. GUNTHER ETAL DEVICE FOR DEPOSITING A LIGHT-DIFFUSING comma on SURFACES Filed Oct. 1. 1951 FIG. I

m m E V m G\ J NNAR GEORG JOHAN GUNTHER, GOSTA BIRGER ROSENGREN.

Y IDJYIAJL ATTORNEY United States Patent DEVICE FOR DEPOSITING A LIGHT-DIFFUSING COATING ON SURFACES Gunnar Georg Johan Giinther and Giista Birger Rosengren, Stockholm, Sweden This invention relates to a device for manufacture of a light-diffusing coating on surfaces, especially inside glass vessels, by thermal decomposition of a volatilizable Enedium to form minute particles deposited on the surace.

As an example of such a coating the manufacture of so-called silica-coatings can be mentioned, that is coatings of minute grains of SiO2, as an anti-dazzle protection in electric lamps, replacing frosted or opal glass. In this ethylsilicate is burnt 01f, usually under feed of oxygen, which ethylsilicate is evaporated and burnt off in a little bowl introduced into the glass bulb.

The demands on the smoothness and appearance of these coatings are great which, however, seem to be dilficult to meet owing to the fact that the ethylsilicate sprinkles from the combustion bowl and that silicon dioxide deposes in layers around the edge of the bowl and reduces the width of the opening.

The invention relates to a special design of a container for heating and combustion respectively of the volatilizable medium. According to the invention the container is given a spherical or still better onion-shaped transverse section with an opening at the top, through which a rod is inserted, standing in the container and functioning as a cleaning organ. Most suitably means are arranged, furthermore, in order to bring a flow of 7 oxygen around the container for intensifying the combustion of the medium.

By the fact that the combustion container tapers upwards all sprinkling is avoided. The rod functions as a cleaning organ. As soon as the opening begins to be reduced owing to deposited crusts it is only necessary to deliver some knocks on the upper part of the rod in order to have the crusts come loose and drop 011. The form of the container also affords another good effect during the coating of lamp bulbs, etc. Before the bulb has been put on over the container, the oxygen gas flow sweeps up along the outside of the container and cools down the container, so that the flame is substantially reduced. In that the bulb is being threaded on the container the vapours from the volatilizable medium are mixed with the oxygen gas and an intense flame 1s obtained which gets the container warm and increases the combustion from this. That the container thus automatically functions as a pilot burner at non-coat ng is not only to advantage regarding saving of the volat1l1za ble medium but favourable from hygienic pomt of v1ew by the fact that the dust formation is considerably reduced.

An apparatus for coating on lamp bulbs etc. is shown in the enclosed drawing in Fig. 1. Fig. 2 shows the combustion container in transverse section in somewhat greater scale.

On a wall 8 a bracket 9 is placed Wl'llCh 1n 1ts upper arm 12 has a bedding 11 inserted for a vertically standing casing 10. The casing is supported at its lower end by a bearing ring 15 placed on a lower arm 16 of the bracket and is forced to rotate by means of a belt pulley 14 threaded on the casing. The belting is shown at 13.

The casing 10 is, in its upper part, ended by a coneshaped seat 6, on which the neck part 7 of the lamp bulb 4 is threaded in order that the bulb 4 is forced to rotate with the casing 10.

In the middle of the casing 10 a tube 5 is inserted which at the bottom is screwed into an opening in the arm 16, at the bottom of which the tube is lengthened with a T-fitting 17. In one of the pipe sockets of the T- fitting a tube 19 is inserted which is in connection with an oxygen gas container. Into another pipe socket a tube 18 is screwed which continues up the middle of the tube 5.

A hose 21) is at the bottom threaded over the tube 18. This is connected with a flow spout of a storage vessel (not shown) for the liquid which shall be subjected to evaporation and burning off.

At the top of the tube 18 a combustion container 2 is screwed in for the liquid. This container has an onion-shaped transverse section and is provided with a pipe socket 23 at the bottom, inserted into the tube 18. At the top the container has an opening 21 through which a rod 1 is inserted, the upper part of which rests against one side of the edge of the opening and the lower part of the same rests on the bottom of the container.

The liquid 22 in the container 2 is, by self-flow from the storage vessel, held on a constant level. The up wards tapering form of the container 2 prevents the liquid from sprinkling and forms the blaze in an upturned flame. The oxygen gas escapes through the opening 3 from the space between the tubes 5 and 18. If no bulb is threaded on, the oxygen gas flow sweeps over the outside of the container 2 cooling the same and at the same time it is only very little mixed with the vapour from the opening 21. The burner device due to this burns with a small fuel saving-flame. As soon as the bulb is threaded on, the flame forms a vault downwards and sweeps over the vessel so that this becomes warm and the flame intense. The coating is carried out owing to this very rapidly, namely in a few seconds.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

In a device for manufacture of a light-diffusing coating on surfaces, especially inside glass vessels, by thermal decomposition of a volatilizable medium to form minute particles deposited on the surface, a substantially onion-shaped medium heating and burning 01f container having an opening at the top and a smaller opening at the bottom, a rod inserted loosely through the top opening in the container having its lower end resting on the inside of said container and operable as a cleaning organ for said smaller opening, a medium storage vessel connected with said container and constantly supplying medium to said container in dependence on the evaporation and burning off thereof, means to introduce a flow of oxygen around the outside of said container in a direction from the bottom thereof upwardly for combustion of the medium, and means for holding the bulb over said container for deposition of the coating medium, and means for rotating said holding means with said bulb thereon.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,123,706 Biggs July 12, 1938 2,164,332 Macksoud July 4, 1939 2,445,310 Chilowsky July 20, 1948 2,489,259 Bechard Nov. 29, 1949 2,545,896 Pipkin Mar. 20, 1951 2,593,920 Reynolds Apr. 22, 1952 

